New control approach for a PV-diesel autonomous power system

A new control scheme for the hybrid photovoltaic-diesel single-phase autonomous power system is proposed. The main advantage of this scheme is that the voltage control is accomplished by the interface inverter without need to the automatic voltage regulator of the diesel-driven generator. Unlike three-phase systems, frequency and voltage control in single-phase autonomous power systems imposes additional complexity. This is due to the pulsating nature of the single-phase loads instantaneous power at twice the rated frequency that may degrade the control efficacy. This obstacle is addressed in this paper and a new scheme is presented. The approach includes three control loops for maximum power tracking, voltage control and frequency control. The generator field current is held constant at its nominal value avoiding the saturation in the field circuit. A robust fuzzy logic controller is adopted for the speed control loop of the diesel engine. The dynamic performance of the system is investigated under different operating conditions.